File content as of revision 5:18920a7a693e:

 /* mbed library for 128*160 pixel display TFT based on S6D0151 LCD Controller
  *
  */

#include "S6D0151_TFT.h"
#include "mbed.h"

#define BPP         16                  // Bits per pixel                

S6D0151_TFT::S6D0151_TFT(PinName mosi, PinName miso, PinName sclk, PinName cs, PinName reset, const char *name)
        : _spi(mosi, miso, sclk), _cs(cs), _reset(reset),GraphicsDisplay(name) {
    tft_reset();
    orientation = 0;
    char_x = 0;
}


int S6D0151_TFT::width() {
    if (orientation == 0 || orientation == 2) return 128;
    else return 160; 
}


int S6D0151_TFT::height() {
    if (orientation == 0 || orientation == 2) return 160;
    else return 128; 
}


void S6D0151_TFT::set_orientation(unsigned int o) {
    orientation = o;
    /* I can't understand rotation methods. 
       Maybe , S6D0151 can NOT conversion row and column.
       but i can conversion up and down.
       orientation=0 : Normal FPC side bottom.
       orientation=2 ; Reverse FPC side is Top.  
    */
    switch (orientation) {
        case 0:
            regwr(0x0001,0x0014);   //DRIVER OUTPUT CONTROL (R01h)
            break;
        case 1:
            //wr_reg(ST7735_MADCTL, 0x0060);
            break;
        case 2:
            regwr(0x0001,0x0314);   //DRIVER OUTPUT CONTROL (R01h)
            break;
        case 3:
            //wr_reg(ST7735_MADCTL, 0x00A0);
            break;
    }
}

void S6D0151_TFT::wr_dat_start(void) {
//    _rs = 1; //  rs high, cs low for transmitting data
    _cs = 0;
    _spi.write( 0x72 );     // Start byte
}



void S6D0151_TFT::wr_dat_stop (void) {
    _cs = 1;
}


void S6D0151_TFT::set_start_address(int left,int top){
    unsigned short addr;
    addr = (((top&0xff)<<8)|(left&0xff));
    
    regwr( 0x0021 , addr );
}

void S6D0151_TFT::reverse(int rev){
    if(rev == TFT_REVERSE_ON){
        regwr(0x0007,0x0033); //DISPLAY CONTROL (R07h)
    } else {
        regwr(0x0007,0x0037); //DISPLAY CONTROL (R07h)
    }
    // X X X PT1 PT0 X X SPT X X GON DTE CL REV D1 D0
    //GON=1,DTE=1 VGH/VGL Normal operation
    //Rev bit mean Color reverse.
    //REV=1 Displays all character and graphics display sections with Reverse
    //D[1:0]=11 Display is RAM data
}

/**
*/
void S6D0151_TFT::regwr(unsigned short reg,unsigned short dat){
    int data;
    _cs = 0;
    _spi.write(0x70);   // RW=0,ID=0,RS=0(Index Register write)
    data = (reg>>8)&0x00ff;
    _spi.write( data );
    data = (reg   )&0x00ff;
    _spi.write( data );
    _cs = 1;
    wait_us(1);         // cs=high Time has not been defined.
    _cs = 0;
    _spi.write(0x72);   // RW=0,ID=0,RS=1(data write)
    data = (dat>>8)&0x00ff;
    _spi.write( data );
    data = (dat   )&0x00ff;
    _spi.write( data );
    _cs = 1;
}
void S6D0151_TFT::reg0(unsigned short reg){
    int data;
    _cs = 0;
    _spi.write(0x70);   // RW=0,ID=0,RS=0(Index Register write)
    data = (reg>>8)&0x00ff;
    _spi.write( data );
    data = (reg   )&0x00ff;
    _spi.write( data );
    _cs = 1;
}
    
void S6D0151_TFT::tft_reset() {
    // init SPI
    _spi.format(8,3);                // 8 bit spi mode 3
    _spi.frequency(6000000);         // 6Mhz SPI clock ... 10Mhz is maximum for display
    
    _cs = 0;
    _reset = 1;
    wait_ms(500);
    _reset = 0;                       // reset
    wait_ms(500);
    _reset = 1;
    wait_ms(500);
    
    /* Start Initial Sequence ----------------------------------------------------*/
    /* follow code is aitendo demo-code...........................................*/
    /* I have changed the part in the demo code to reference----------------------*/
    regwr(0x0007,0x0020);   //DISPLAY CONTROL (R07h)
    // X X X PT1 PT0 X X SPT X X GON DTE CL REV D1 D0
            //PT[1:0]=00 V63/V0 Normal Drive
            //SPT=0 Split Screen Driving Function is Not performed
            //GON=1,DTE=0 Normal operation
            //CL=0 262,144 colors / 65,536 colors
            //REV=0 Displays all character and graphics display sections with Normal
            //D[1:0]=00 the internal display operation halts and the display is off.
    
    regwr(0x00b6,0x013f);   //Module Vendor (RB6h)
    // TEST_IN4 TEST_IN3 X X X X PSMD1(0) PSM D0(1) X X 1 1 1 1 1 1
            //TEST_IN4,TEST_IN3 User can know the Module Vendor through this register is accessed.
            //PSMD[1:0]=01 5680*(1/fosc) Select the power on time delay of step-up circuit.
    
    regwr(0x00b4,0x0010);   //MTP CONTROL (RB4h)
    // X X X MTP_SEL X X X MTP_INIT X X X MTP_WRB X X X MTP_LOAD
        //MTP_SEL=0 VCOMH Control Data is VCM Register
        //MTP_INIT=0
        //MTP_WRB=1 Cannot write MTP data
        //MTP_LOAD=0

    regwr(0x0012,0x00b2);   //POWER CONTROL 2 (R12h)
    // X X X X X X X X SVC3 SVC2 SVC1 SVC0 X 0 VRH5 VRH4
        //SVC Adjust reference voltage of AVDD, VGH, VGL and VCL
        // SVC[3:0]=1011 VCI1=2.76V
   
    regwr(0x0013,0x080e);   //POWER CONTROL 3 (R13h)
    // X X X X VCMR X X X X X X PON VRH3 VRH2 VRH1 VRH0 
        //PON=0 The operational amplifier is stop.
        //VCMR=1 VCOMH voltage=Internal electronic volume
        //VRH[5:0]=1e=011110 VCIR_EXIN X 2.250 = 4.50V
    
    regwr(0x0014,0x5bca);   //POWER CONTROL 4 (R14h)
    // X VDV6 VDV5 VDV4 VDV3 VDV2 VDV1 VDV0 VCOMG VCM6 VCM5 VCM4 VCM3 VCM2 VCM1 VCM0
        //VDV Set the alternating amplitudes of Vcom at the Vcom alternating drive.
        // VDV[6:0]=5b=1011011 GVDD x 0.984 
        //VCOMG=1 VcomL voltage can output to negative voltage.
        //Set the VcomH voltage (a high-level voltage at the Vcom alternating drive).
        // VCM[6:0]=1001010 GVDD x 0.8085
    
    regwr(0x0061,0x0018);   //OSCILLATOR CONTROL (R61h)
    // X X X X X X X X X X X RADJ4 RADJ3 RADJ2 RADJ1 RADJ0
        //RADJ[4:0]=11000 Oscillation Speed=x 1.000 Default
   
    regwr(0x0010,0x190c);   //POWER CONTROL 1 (R10h)
    // DSTB X SAP2 SAP1 SAP0 BT2 BT1 BT0 DC2 DC1 DC0 AP2 AP1 AP0 SLP STB
        //DSTB=0 Noraml
        //Adjust the slew-rate of the operational amplifier for the source driver.
        // SAP[2:0]=011 Medium Medium
        //BT[2:0]=001 VGH=AVDDx3 VGL=-(AVDDx2) VGH = Vci1 X six times
        //DC[2:0]=000 AVDD,VCL=DCCLK/1 VGH,VGL=DCCLK/2
        //AP[2:0]=011 Amount of Current in Operational Amplifier=Medium
        //SLP=0 setting Sleep. Normal mode
        //STB=0 setting standby. normal mode
    wait_ms(80);   
   
    regwr(0x0013,0x081e);   //POWER CONTROL 3 (R13h)
    // X X X X VCMR X X X X X X PON VRH3 VRH2 VRH1 VRH0 
        //PON=1 The operational amplifier is Start.
        //VCMR=1 VCOMH voltage=Internal electronic volume
        //VRH[5:0]=1e=011110 VCIR_EXIN X 2.250 = 4.50V
    wait_ms(20);   
   
    regwr(0x0001,0x0014);   //DRIVER OUTPUT CONTROL (R01h)
    // X X X DPL EPL SM GS SS X X X NL4 NL3 NL2 NL1 NL0
    // demo code was 0x0114,SS bit=1 is reverse horizontal.
        //DPL=0,EPL=0
        //SM=0 even/odd division is selected
        //GS=0 G1 is output first and G160 is finally output.
        //SS=1 Select the direction of the source driver channel in pixel unit.
        //NL[4:0]=10100 Drive Duty=384 X 160 dots 160 G1 to G160
    
    regwr(0x0002,0x0100);   //LCD INVERSION CONTROL (R02h)
    // X X X X X X FL1 FL0 X X X FLD X X X X
        //FL[1:0]=01 FLD=0 Line Inversion-1 field interlace

    regwr(0x0003,0x0030);   //ENTRY MODE (R03h)
    // X X X BGR X X MDT1 MDT0 X X ID1 ID0 AM X X X
        //BGR=0 assigned to {R, G, B}.When 18-bit data is written to GRAM through DB bus
        //MDT[1:0]=00 260k color data is transferred by 3or2-times(setting for IM) Data Transfer.
        // When user wants to transfer 260k color data on 8/16-bit parallel bus
        //ID[1:0]=11 When ID[1], ID[0] = 1, the address counter (AC) is automatically increased by 1 after the data is written to the GRAM
        //AM=0 the data is continuously written in horizontally.
   
    regwr(0x0008,0x0202);   //BLANK PERIOD CONTROL 1 (R08h)
    // X X X X FP3 FP2 FP1 FP0 X X X X BP3 BP2 BP1 BP0
        //FP[3:0]=0010
        //BP[3:0]=0010
        //Number of Raster Periods In Front (Back) Porch Default=2;
    
    regwr(0x000b,0x0000);   //FRAME CYCLE CONTROL (R0Bh)
    // X X X X X X DIV1 DIV0 X X X X RTN3 RTN2 RTN1 RTN0
        //DIV[1:0]=00 Division Ratio=1 Internal operation clock frequency=fosc/1
        //RTN[3:0]=Clock Cycles per horizontal Line= 16 (INCLKs)
    
    regwr(0x000c,0x0000);   //EXTERNAL DISPLAY INTERFACE CONTROL (R0Ch)
    // X X X X X X X RM X X DM1 DM0 X X RIM1 RIM0
        //RM=0 GRAM Access Interface=System interface
        //DM[1:0]=00 Display operation mode = Internal clock operation
    
    regwr(0x0061,0x0018);   //OSCILLATOR CONTROL (R61h)
    // X X X X X X X X X X X RADJ4 RADJ3 RADJ2 RADJ1 RADJ0
        //RADJ[4:0]=11000 Oscillation Speed=x 1.000 Default
   
    regwr(0x0069,0x0000);   //DC/DC CONVERT LOW POWER MODE SETTING (R69h)
    // 0 0 0 0 0 0 0 0 0 0 0 NLDC3 NLDC2 NLDC1 NLDC0 NLPM
        //NLPM=0 Normal operation mode
        //NLDC[1:0]=00 DCCLK/1
        //NLDC[3:2]=00 DCCLK/2
    
    regwr(0x0070,0x0000);   //SOURCE DRIVER PRE-DRIVING PERIOD SETTING (R70h)
    // X X X X X X X X SDT1 SDT0 X X X X EQ1 EQ0
        //STD[1:0]=00 Source Output Delay Control=1 DISP_CK
        //EQ=00 No Equalization Control
    regwr(0x0071,0x0000);   //GATE OUTPUT PERIOD CONTROL (R71h)
    // X X X X GNO1 GNO0 X X X X X X X X X X
        //GN)=00 Non-Overlap Period Control =2 DISP_CKs

    regwr(0x0011,0x0000);   //GAMMA CONTROL 1 (R11h)
    // VR1C X X VRN14 VRN13 VRN12 VRN11 VRN10 X X X VRP14 VRP13 VRP12 VRP11 VRP10
        //VR1C=0 Control step of amplitude positive and negative of 64-grayscale.
        //VRP1[4:0]=00000 Control amplitude positive polarity of 64-grayscale.
        //VRN1[4:0]=00000 Control amplitude negative polarity of 64-grayscale.
 
    /* Gamma settings  -----------------------------------------------------------*/
///////r CONTROL   
    regwr(0x0030,0x0303);    //GAMMA CONTROL 2 (R30h to R37h)
    regwr(0x0031,0x0303);    //GAMMA CONTROL 2 (R30h to R37h)
    regwr(0x0032,0x0303);    //GAMMA CONTROL 2 (R30h to R37h)
    regwr(0x0033,0x0000);    //GAMMA CONTROL 2 (R30h to R37h)
    regwr(0x0034,0x0404);    //GAMMA CONTROL 2 (R30h to R37h)
    regwr(0x0035,0x0404);    //GAMMA CONTROL 2 (R30h to R37h)
    regwr(0x0036,0x0404);    //GAMMA CONTROL 2 (R30h to R37h)
    regwr(0x0037,0x0000);    //GAMMA CONTROL 2 (R30h to R37h)
    regwr(0x0038,0x0707);    //GAMMA CONTROL 2 (R38h)
///////Coordinatioontrol setting   
    regwr(0x0040,0x0000);    // GATE SCAN POSITION (R40h)
    // 1 X X X X X X X X X X X SCN4 SCN3 SCN2 SCN1 SCN0
    //Set the scanning starting position of the gate driver.

    regwr(0x0042,0x9f00);    //1st SCREEN DRIVING POSITION (R42h)
    // SE17 SE16 SE15 SE14 SE13 SE12 SE11 SE10 SS17 SS16 SS15 SS14 SS13 SS12 SS11 SS10

    regwr(0x0043,0x0000);    //2nd SCREEN DRIVING POSITION (R43h)
    // SE27 SE26 SE25 SE24 SE23 SE22 SE21 SE20 SS27 SS26 SS25 SS24 SS23 SS22 SS21 SS20
    regwr(0x0044,0x7f00);    //HORIZONTAL RAM ADDRESS POSITION (R44h)

    regwr(0x0045,0x9f00);    //VERTICAL RAM ADDRESS POSITION (R45h)

    regwr(0x0069,0x0000);    //DC/DC CONVERT LOW POWER MODE SETTING (R69h)
    // 0 0 0 0 0 0 0 0 0 0 0 NLDC3 NLDC2 NLDC1 NLDC0 NLPM
    //NLPM=0 Normal operation mode
    //NLDC[1:0]=00 DCCLK/1
    //NLDC[3:2]=00 DCCLK/2

    regwr(0x0070,0x0000);    //SOURCE DRIVER PRE-DRIVING PERIOD SETTING (R70h)
    // X X X X X X X X SDT1 SDT0 X X X X EQ1 EQ0
    //STD[1:0]=00 Source Output Delay Control=1 DISP_CK
    //EQ=00 No Equalization Control

    regwr(0x0071,0x0000);    //GATE OUTPUT PERIOD CONTROL (R71h)
    // X X X X GNO1 GNO0 X X X X X X X X X X
    //GNO=00 Non-Overlap Period Control =2 DISP_CKs
   
    regwr(0x0073,0x0000); //TEST_KEY (R73h)
    // X X X X X X X X TEST_KEY[7:0]
    //When you want to update MTP data, “A5” should be written to this register.

    regwr(0x00B3,0x0000); //PUMPING CLOCK SOURCE SELECTION (RB3h)
    // X 0 0 0 X 0 1 0 X X X DCR_EX X X X 1
    //Select the source of pumping clock.
    //In RGB mode, DCR_EX should be set before power setting.

    regwr(0x00BD,0x0000); //MTP DATA READ (RBDh)
    // X X X X X X X DISEN X MTP_DOUT[6:0]
    //DISEN=0 Standby mode discharge circuit operation stop.
    //MTP_DOUT MTP data read using MTP_READ register.

    regwr(0x00BE,0x0000); //INTERFACE MODE SELECTION (RBEh)
    // X X X X X X X X X X X IM_SEL IM_3 X X FLM_MSK
    //IM_SEL register selects interface mode.
    //IM_SEL=0 is IM[3:0] setting

    regwr(0x0021,0x0000); //GRAM ADDRESS SET (R21h)
    // AD15 AD14 AD13 AD12 AD11 AD10 AD9 AD8 AD7 AD6 AD5 AD4 AD3 AD2 AD1 AD0
    // You can write initial GRAM address into internal Address Counter (AC).

    reg0(0x0022); //WRITE DATA TO GRAM (R22h)
    // RAM write data (WD17 ~ WB0). Interface mode controls the width of WD
    // Data on DB bus is expanded to 18-bits before being written to GRAM and the data determines grayscale level of S6D0151’s source output.
    wait_ms(20);   
   
    regwr(0x0007,0x0020); //DISPLAY CONTROL (R07h)
    // X X X PT1 PT0 X X SPT X X GON DTE CL REV D1 D0
    //PT[1:0]=00 V63/V0 Normal Drive
    //SPT=0 Split Screen Driving Function is Not performed
    //GON=1,DTE=0 Normal operation
    //CL=0 262,144 colors / 65,536 colors
    //REV=0 Displays all character and graphics display sections with Normal
    //D[1:0]=00 the internal display operation halts and the display is off.
    wait_ms(5);   

    regwr(0x0007,0x0021); //DISPLAY CONTROL (R07h)
    // X X X PT1 PT0 X X SPT X X GON DTE CL REV D1 D0
    //D[1:0]=01 the internal display operation halts and the display is off.

    regwr(0x0007,0x0027); //DISPLAY CONTROL (R07h)
    // X X X PT1 PT0 X X SPT X X GON DTE CL REV D1 D0
    //REV=1 Displays all character and graphics display sections with Reverse
    //D[1:0]=11 the internal display operation halts and the display is off.

    wait_ms(50);   
    regwr(0x0007,0x0037); //DISPLAY CONTROL (R07h)
    // X X X PT1 PT0 X X SPT X X GON DTE CL REV D1 D0
    //GON=1,DTE=1 VGH/VGL Normal operation
    //Rev bit mean Color reverse.
    //REV=1 Displays all character and graphics display sections with Reverse
    //D[1:0]=11 Display is RAM data

    /*　Up to here, demo code reference partsas ------------------------------*/

    WindowMax ();
}


void S6D0151_TFT::pixel(int x, int y, int color) {
  if ((x >= width()) || (y >= height())) return;

  window(x,y,1,1);

    wr_dat_start();
    _spi.write(color >> 8);
    _spi.write(color & 0xFF);     
    wr_dat_stop();

}

void S6D0151_TFT::window (unsigned int x, unsigned int y, unsigned int w, unsigned int h) {
    unsigned int hea,hsa,vea,vsa,dd;
    hea=x+w-1;
    hsa=x;
    vea=y+h-1;
    vsa=y;

    dd=((hea&0xff)<<8)|(hsa&0xff);
    regwr(0x0044, dd );    //HORIZONTAL RAM ADDRESS POSITION (R44h)
    dd=((vea&0xff)<<8)|(vsa&0xff);
    regwr(0x0045, dd );    //VERTICAL RAM ADDRESS POSITION (R45h)

//    set_start_address(hea,vea);
    set_start_address(hsa,vsa);
    reg0(0x0022);   //Write data to GRAM
}


void S6D0151_TFT::WindowMax (void) {
    window (0, 0, width(),  height());
}


void S6D0151_TFT::cls (void) {
    unsigned int i;
    WindowMax();

    wr_dat_start();
    for (i = 0; i < ( (width()+1) * (height()+3)); i++) {
        _spi.write(_background >> 8);    
        _spi.write(_background & 0xFF);    
    }
    wr_dat_stop();
}


void S6D0151_TFT::circle(int x0, int y0, int r, int color) {

    int draw_x0, draw_y0;
    int draw_x1, draw_y1;
    int draw_x2, draw_y2;
    int draw_x3, draw_y3;
    int draw_x4, draw_y4;
    int draw_x5, draw_y5;
    int draw_x6, draw_y6;
    int draw_x7, draw_y7;
    int xx, yy;
    int di;
    WindowMax();
    if (r == 0) {       /* no radius */
        return;
    }

    draw_x0 = draw_x1 = x0;
    draw_y0 = draw_y1 = y0 + r;
    if (draw_y0 < height()) {
        pixel(draw_x0, draw_y0, color);     /* 90 degree */
    }

    draw_x2 = draw_x3 = x0;
    draw_y2 = draw_y3 = y0 - r;
    if (draw_y2 >= 0) {
        pixel(draw_x2, draw_y2, color);    /* 270 degree */
    }

    draw_x4 = draw_x6 = x0 + r;
    draw_y4 = draw_y6 = y0;
    if (draw_x4 < width()) {
        pixel(draw_x4, draw_y4, color);     /* 0 degree */
    }

    draw_x5 = draw_x7 = x0 - r;
    draw_y5 = draw_y7 = y0;
    if (draw_x5>=0) {
        pixel(draw_x5, draw_y5, color);     /* 180 degree */
    }

    if (r == 1) {
        return;
    }

    di = 3 - 2*r;
    xx = 0;
    yy = r;
    while (xx < yy) {

        if (di < 0) {
            di += 4*xx + 6;
        } else {
            di += 4*(xx - yy) + 10;
            yy--;
            draw_y0--;
            draw_y1--;
            draw_y2++;
            draw_y3++;
            draw_x4--;
            draw_x5++;
            draw_x6--;
            draw_x7++;
        }
        xx++;
        draw_x0++;
        draw_x1--;
        draw_x2++;
        draw_x3--;
        draw_y4++;
        draw_y5++;
        draw_y6--;
        draw_y7--;

        if ( (draw_x0 <= width()) && (draw_y0>=0) ) {
            pixel(draw_x0, draw_y0, color);
        }

        if ( (draw_x1 >= 0) && (draw_y1 >= 0) ) {
            pixel(draw_x1, draw_y1, color);
        }

        if ( (draw_x2 <= width()) && (draw_y2 <= height()) ) {
            pixel(draw_x2, draw_y2, color);
        }

        if ( (draw_x3 >=0 ) && (draw_y3 <= height()) ) {
            pixel(draw_x3, draw_y3, color);
        }

        if ( (draw_x4 <= width()) && (draw_y4 >= 0) ) {
            pixel(draw_x4, draw_y4, color);
        }

        if ( (draw_x5 >= 0) && (draw_y5 >= 0) ) {
            pixel(draw_x5, draw_y5, color);
        }
        if ( (draw_x6 <=width()) && (draw_y6 <= height()) ) {
            pixel(draw_x6, draw_y6, color);
        }
        if ( (draw_x7 >= 0) && (draw_y7 <= height()) ) {
            pixel(draw_x7, draw_y7, color);
        }
    }
    return;
}

void S6D0151_TFT::fillcircle(int x, int y, int r, int color) {
    int i;
    for (i = 0; i <= r; i++)
        circle(x,y,i,color);
}

void S6D0151_TFT::fillcircle2(int x0, int y0, int r, int color){
    int x = -r, y = 0, err = 2-2*r, e2;
    do {
        vline(x0-x, y0-y, y0+y, color);
        vline(x0+x, y0-y, y0+y, color);
        e2 = err;
        if (e2 <= y) {
            err += ++y*2+1;
            if (-x == y && e2 <= x) e2 = 0;
        }
        if (e2 > x) err += ++x*2+1;
    } while (x <= 0);
}

void S6D0151_TFT::hline(int x0, int x1, int y, int color) {
    int w;
    w = x1 - x0 + 1;
    window(x0,y,w,1);
    wr_dat_start();
    for (int x=0; x<w; x++) {
        _spi.write(color >> 8);
        _spi.write(color);
    }
    wr_dat_stop();
    return;
}



void S6D0151_TFT::vline(int x, int y0, int y1, int color) {
    int h;
    h = y1 - y0 + 1;
    window(x,y0,1,h);
    wr_dat_start();
    for (int y=0; y<h; y++) {
        _spi.write(color >> 8);
        _spi.write(color);
    }
    wr_dat_stop();
    return;
}



void S6D0151_TFT::line(int x0, int y0, int x1, int y1, int color) {
    WindowMax();
    int   dx = 0, dy = 0;
    int   dx_sym = 0, dy_sym = 0;
    int   dx_x2 = 0, dy_x2 = 0;
    int   di = 0;

    dx = x1-x0;
    dy = y1-y0;

    if (dx == 0) {        /* vertical line */
        if (y1 > y0) vline(x0,y0,y1,color);
        else vline(x0,y1,y0,color);
        return;
    }

    if (dx > 0) {
        dx_sym = 1;
    } else {
        dx_sym = -1;
    }
    if (dy == 0) {        /* horizontal line */
        if (x1 > x0) hline(x0,x1,y0,color);
        else  hline(x1,x0,y0,color);
        return;
    }

    if (dy > 0) {
        dy_sym = 1;
    } else {
        dy_sym = -1;
    }

    dx = dx_sym*dx;
    dy = dy_sym*dy;

    dx_x2 = dx*2;
    dy_x2 = dy*2;

    if (dx >= dy) {
        di = dy_x2 - dx;
        while (x0 != x1) {

            pixel(x0, y0, color);
            x0 += dx_sym;
            if (di<0) {
                di += dy_x2;
            } else {
                di += dy_x2 - dx_x2;
                y0 += dy_sym;
            }
        }
        pixel(x0, y0, color);
    } else {
        di = dx_x2 - dy;
        while (y0 != y1) {
            pixel(x0, y0, color);
            y0 += dy_sym;
            if (di < 0) {
                di += dx_x2;
            } else {
                di += dx_x2 - dy_x2;
                x0 += dx_sym;
            }
        }
        pixel(x0, y0, color);
    }
    return;
}




void S6D0151_TFT::rect(int x0, int y0, int x1, int y1, int color) {

    if (x1 > x0) hline(x0,x1,y0,color);
    else  hline(x1,x0,y0,color);

    if (y1 > y0) vline(x0,y0,y1,color);
    else vline(x0,y1,y0,color);

    if (x1 > x0) hline(x0,x1,y1,color);
    else  hline(x1,x0,y1,color);

    if (y1 > y0) vline(x1,y0,y1,color);
    else vline(x1,y1,y0,color);

    return;
}



void S6D0151_TFT::fillrect(int x0, int y0, int x1, int y1, int color) {

    int h = y1 - y0 + 1;
    int w = x1 - x0 + 1;
    int pixel = h * w;
    window(x0,y0,w,h);
    wr_dat_start();
    for (int p=0; p<pixel; p++) {
        _spi.write(color >> 8);
        _spi.write(color & 0xFF);
    }
    wr_dat_stop();
    return;
}



void S6D0151_TFT::locate(int x, int y) {
    char_x = x;
    char_y = y;
}



int S6D0151_TFT::columns() {
    return width() / font[1];
}



int S6D0151_TFT::rows() {
    return height() / font[2];
}



int S6D0151_TFT::_putc(int value) {
    if (value == '\n') {    // new line
        char_x = 0;
        char_y = char_y + font[2];
        if (char_y >= height() - font[2]) {
            char_y = 0;
        }
    } else {
        character(char_x, char_y, value);
     }
    return value;
}




void S6D0151_TFT::character(int x, int y, int c) {
    unsigned int hor,vert,offset,bpl,j,i,b;
    unsigned char* zeichen;
    unsigned char z,w;

    if ((c < 31) || (c > 156)) return;   // test char range

    // read font parameter from start of array
    offset = font[0];                    // bytes / char
    hor = font[1];                       // get hor size of font
    vert = font[2];                      // get vert size of font
    bpl = font[3];                       // bytes per line

    if (char_x + hor > width()) {
        char_x = 0;
        char_y = char_y + vert;
       if (char_y >= height() - font[2]) {
            char_y = 0;
        }
    }

    window(char_x, char_y,hor,vert); // char box
    wr_dat_start();
    zeichen = &font[((c -32) * offset) + 4]; // start of char bitmap
    w = zeichen[0];                          // width of actual char

    for (j=0; j<vert; j++) {  //  vert line
        for (i=0; i<hor; i++) {   //  horz line
            z =  zeichen[bpl * i + ((j & 0xF8) >> 3)+1];
            b = 1 << (j & 0x07);
            if (( z & b ) == 0x00) {
                _spi.write(_background >> 8);
                _spi.write(_background & 0xff);
            } else {
                _spi.write(_foreground >> 8);
                _spi.write(_foreground & 0xff);
            }
        }
    }
    wr_dat_stop();
    if ((w + 2) < hor) {                   // x offset to next char
        char_x += w + 2;
    } else char_x += hor;
}

void S6D0151_TFT::set_font(unsigned char* f) {
    font = f;
}



void S6D0151_TFT::Bitmap(unsigned int x, unsigned int y, unsigned int w, unsigned int h,unsigned char *bitmap) {
    unsigned int    i,j;
    unsigned short *bitmap_ptr = (unsigned short *)bitmap;
    window(x, y, w, h);
    wr_dat_start();
    for (j = 0; j < h; j++) {        //Lines
        for (i = 0; i < w; i++) {     // copy pixel data to TFT

            _spi.write(*bitmap_ptr >> 8);  
            _spi.write(*bitmap_ptr);    // one line

            bitmap_ptr++;
        }
    }
    wr_dat_stop();
}